But for the two-time DWTS champ, life wasn't always so smooth: As a child, Burke was repeatedly molested by a friend of her family's – and testified against him in court, helping send him to prison for nearly two decades.

"I'm telling my story," says Burke, 26, who opens up about the molestation – and other struggles, including physical abuse by two former boyfriends – in her new book Dancing Lessons, (coauthored by PEOPLE senior writer Monica Rizzo). "They're not secrets. There's no shame."

Burke's abuser was a retired mailman who was trusted and well liked in Burke's Bay Area community. He would sometimes pick Burke up from school and do odd jobs around her home. The assaults began when she was 5.

After he was accused of targeting other children, Burke acknowledged her own abuse. But, still reeling from her parents' split when she was a baby, she was wracked with confusion.

"I felt guilty for wanting his love and affection," she says, calling testifying against him "the hardest thing I've ever done ... I saw his face and lawyers were asking me these questions and I was like, 'What am I doing? Did he even do anything wrong?' "

Eventually, with the man in prison and years of therapy, Burke came to see just how wrong her abuser was.

Now, with season 12 of DWTS beginning in March, Burke is ready to tell her story. "If I can help just one person," she says, "for me that's all that matters."

For more on Burke's story check out the new issue of PEOPLE on newsstands Friday